"The thing that astounds me more than anything else is," Levin continued, "the idea that people in Pakistan higher up in the intelligence service or their police or their local officials didn't know he was there. I find that difficult to believe."

The Senate Armed Services Committee, Levin said, has already started a preliminary investigation into Pakistan's involvement and, depending on the results of that investigation, will decide whether to hold public hearings to investigate further.

"We need these questions answered about whether or not the top level of the Pakistan government knew or was told by the ISI, their intelligence service, about anything, about this suspicious activity for five years in a very, very centralized place," Levin said.

Beyond his suspicions about Pakistan's role in harboring bin Laden, Levin said he has "no doubt" that the highest levels of the Pakistani government are protecting other terrorist targets -- such as Taliban leader Mullah Omar and the leaders of the Haqqani terror network -- who have been responsible for the deaths of American troops in Afghanistan.

"They cross the border into Afghanistan and kill us," Levin said. "And the Pakistan government knows where they're at, they're openly living in north Waziristan. The Pakistan government knows where the so-called Quetta Shura is, which is the Afghan Taliban leadership in Pakistan."

Mullah Omar?

"Mullah Omar," Levin responded. "In Pakistan. They live openly."

"These people are killing us. Killing our Afghan allies. Killing our coalition partners by crossing the border," Levin said. "They're being given a safe haven in Pakistan. So the government of Pakistan is going to continue to say they didn't know bin Laden was there. It's kind of hard to believe that higher level people didn't know, but they'll continue to say that. But what they won't say is that they don't know where the Haqqani terrorists are because they do know, and they've told us they know."

Asked if the "highest level" of the Pakistani government knows where these terrorist leaders are, Levin said, "There's no doubt. They live openly and we've talked to the Pakistani government about it."